The production of lead-free or substantially lead-free fuels is, of course, well within the ordinary skill in the art. It is also well known that the public and government have been interested in eliminating or at least significantly reducing the amount of pollutants emitted to the atmosphere as the result of combustion of various fuels in internal combustion engines. Lead and its compounds, especially alkyl lead, R4Pb, are not recognized as naturally occurring in crude oil. However, lead is found in crude oils and their distillate fractions and is usually traced to the lead contamination in gasoline.
Although non-leaded gasolines may be produced at the refinery with significant low lead levels to meet the legal requirements, occasionally fuels will absorb small but significant amounts of lead compounds from storage, or transport of fuels in lead contaminated tanks and pipelines, which may exceed the legal limit. A number of processes have been designed to remove heavy metals from crude oil, fuel, and water with varying degrees of success.
U.S. Pat. No. 4,048,061 issued on Sep. 13, 1977 to George C. Blytas teaches a process for reducing the level of compounds of certain metals from hydrocarbon liquids by contacting metal compound-bearing hydrocarbons with acidified active carbon. One major problem with this patent is that the amounts of reactants utilized will vary depending upon the particular active carbon as well as the oxidizing/acidic fluid employed. It was also found that the acidified active carbon will only partially be removed from the fuels and that some commercially employed additives are used and remain in the fuel.
U.S. Pat. No. 4,070,282 issued on Jan. 24, 1978 to Jack M. Otto teaches a method of removing ionizable organolead compounds from aqueous liquid compositions. However, this patent does not teach the use of ozone to oxidize organolead compounds to form insoluble lead oxide polymers for easier removal of the polymer and thus the lead.
The need for the removal of metals is evidenced by the fact that their presence in hydrocarbon charge stocks conducted to catalytic cracking and catalytic reforming process units is known to poison and shorten the life of the catalyst with which such metal contaminated stocks come into contact. It is also desirable to remove trace metals from lubricating oils or to recover soluble metal catalysts from reactor effluents or polymer solutions.
From the foregoing, it will be appreciated that there is a need in the art for a method of removing lead from both aqueous and non-aqueous compositions, which are environmentally safe. The present invention is directed to overcoming one, or more, of the problem set forth above.